The roles of microfabricated components for miniaturized chemical analysis systems are reviewed and the fundamental advantages of these components are illustrated in typical analysis and separation systems, including mass spectrometry, electroanalytical chemistry, capillary electrophoresis, and chromatography. In each instance the scaling laws that affect the resolution of the miniaturized instrument are supported by key enabling micromachined components. Micromachined components are also enabling elements for system integration and for coupling multiple techniques together in parallel or cascade.